Rotating Helices and Frames
The apparatus on this page derives directly from Michael Faraday's
1821 discovery that a wire would rotate around a magnetic pole. A replica of his
apparatus demonstrate this phenomenon is shown on another page.
In 1828 the Englishman, Francis Watkins, suggested the rotating wire frame arrangement
shown at the left, below. The current runs downward in both wire frames, and they
contrarotate about the North and South poles of the U-magnet.
A variation on the theme is shown at the right, below.
The wire helices have downward current components that experience a torque
due to the magnetic field. Again, the helices contrarotate. Originally
the central pillar was set higher, allowing the downward-projecting points
to make contact with mercury in the cups at the tops of the helices. Both
of these instruments are at Transylvania University in Lexington, Kentucky.
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